Gas injector assembly comprising a compact vacuum-controlled second sealing seat

Abstract

The present invention relates to a gas injector assembly for injecting a gaseous medium, said assembly comprising a gas injector (1), a shut-off valve (300), a control valve unit (8), and a rail (400). The gas injector comprises: a closing element (2) which opens and closes a through-opening (3) at a first sealing seat (4); an actuator (5) for actuating the closing element (2); and a resetting element (6) for resetting the closing element (2). The shut-off valve (300) is arranged between the gas injector (1) and the rail (400) and comprises: a second sealing seat (7) which is arranged upstream of the gas injector (1) in the direction of flow of the gaseous medium, the second sealing seat (7) opening and closing a gas flow path (A) through the shut-off valve; and a vacuum connection (80) which is arranged upstream of the second sealing seat (7) in the direction of flow of the shut-off valve (300). The control valve unit (8) comprises a control valve (81; 100, 200) which is fluidically connected to the vacuum connection (80) and is designed to connect the vacuum connection (80) to a vacuum source (82) in order to open the second sealing seat (7).

Description

[0001] Description

[0002] title

[0003] Gas injector arrangement with vacuum-controlled second sealing seat in a compact design

[0004] State of the art

[0005] The present invention relates to a gas injector arrangement with a gas injector for injecting a gaseous medium, in particular hydrogen or natural gas, with a second, pressure-controlled sealing seat, in a particularly compact design, and to an internal combustion engine.

[0006] Gas injector assemblies are known in various designs from the state of the art. Compared to injectors for liquid fuels, the technical requirements for gas injectors and gas injector assemblies are significantly different. One problem with gas injectors, for example, is sealing the gas injector over extended periods. In particular, it is important to prevent gaseous fuel from escaping from the gas injector into a combustion chamber, for example, when an internal combustion engine is switched off despite the sealing seat being closed, and possibly entering the environment. This must be avoided at all costs.

[0007] Disclosure of the invention

[0008] The gas injector arrangement according to the invention for injecting a gaseous medium with the features of claim 1 has the advantage that, even when the gas injector is closed for extended periods, a significant reduction in the potential loss of the gaseous medium from the gas injector is possible. Furthermore, in order to open a second sealing seat of the gas injector, in particular an elastomer sealing seat, not only improved sealing but also reliable opening can be achieved even with large sealing diameters of the second sealing seat. The gas injector according to the invention has a very simple and cost-effective construction. The gas injector can also close quickly and easily at the second sealing seat, so that an undesirable loss of medium to be injected can be prevented after an internal combustion engine is switched off.

[0009] This is achieved according to the invention in that the gas injector arrangement comprises a gas injector, a rail, a controllable additional shut-off valve, and a control valve unit. The gas injector comprises a closing element configured to open and close a through-opening at a first sealing seat. Furthermore, the gas injector comprises an actuator, in particular a magnetic actuator, for actuating the closing element. A return element is provided to return the closing element to a closed initial position. The rail comprises an inlet bore, in particular in the main extension direction of the rail, and at least one branch bore. It should be noted here that the term "bore" is intended to encompass components manufactured by machining processes as well as by casting processes, additive processes, or other processes.The controllable shut-off valve is arranged in the branch bore of the rail. The gas injector is in fluid communication with the shut-off valve, so that a gaseous medium to be injected can be fed from the rail to the gas injector via the shut-off valve. The shut-off valve has a second sealing seat, which opens and closes a gas flow path and the branch bore of the rail in the direction of the gas injector. The shut-off valve has a vacuum connection to the control valve unit. The control valve unit is configured to connect a vacuum source to the vacuum connection on the shut-off valve in order to open the second sealing seat. The second sealing seat can thus be opened by vacuum. Furthermore, since the gas injector and the shut-off valve are two separate components, the gas injector itself can be very compact and small in size. In particular, the gas injector has a very short design in the axial direction.The existing pressure of the gaseous medium can preferably be used to close the second sealing seat on the shut-off valve. The vacuum source has a lower pressure than the gaseous medium to be injected and preferably a pressure below ambient pressure. Thus, the provision of two sealing seats ensures that the gas injector remains gas-tight even when the gas injector arrangement is idle for an extended period and the gas injector is not actuated. Even if the first sealing seat, which is directed towards the combustion chamber and in particular blows directly into a combustion chamber, is leaking, the second sealing seat can reduce at least any amount of gaseous medium potentially flowing out of the gas injector to the volume between the first and second sealing seats.Furthermore, the pneumatic actuation of the shut-off valve using vacuum to open the second sealing seat allows for a very simple and cost-effective design. This also prevents heat problems in the gas injector, which could occur, for example, when using electrically actuated shut-off elements.

[0010] Further preferably, the rail has a plurality of branch bores branching off from a single, common inlet bore. This allows, for example, several cylinders of an internal combustion engine to be supplied with gaseous fuel.

[0011] The subclaims show preferred developments of the invention.

[0012] Further preferably, the rail comprises a main bore and a vacuum bore configured to connect the vacuum connection of the shut-off valve to the vacuum source. This makes it possible to dispense with pressure-resistant lines that establish the connection to the vacuum source. This results in significant cost savings both in terms of material costs for such pressure lines and in complex and expensive assembly. Furthermore, by integrating the vacuum bore into the rail, the installation space of the gas injector assembly can be kept very small.

[0013] To ensure a secure seal between the shut-off valve in the branch bore and the rail, the gas injector assembly preferably further comprises a first and a second radial seal. The first and second radial seals seal between the shut-off valve and the branch bore. The first and second radial seals are preferably O-rings. The rail preferably comprises a transverse bore in which the shut-off element is arranged.

[0014] The shut-off valve preferably comprises an axially movable piston. The second sealing seat is preferably formed between the piston and a housing component. The piston enables simple and reliable opening of the second sealing seat by means of negative pressure.

[0015] The gas injector further preferably comprises a third sealing seat arranged on the piston. The third sealing seat opens and closes a connection between a gas flow path, which also leads through the shut-off valve, and the control valve unit. The piston can be moved back and forth between the second and third sealing seats. Thus, the second and third sealing seats are not both closed at the same time.

[0016] Preferably, the third sealing seat is formed between a radially outwardly directed flange on the piston and a stop disc on the housing component of the shut-off valve. The housing component further preferably also serves as a guide component for the piston.

[0017] The piston is preferably a hollow piston with a closed piston end face, wherein the second sealing seat is formed by the piston end face and the housing of the shut-off valve, in particular on a radially inwardly directed projection of the housing. Thus, an axial movement of the piston of the shut-off valve enables the opening and closing of the second sealing seat. The hollow piston preferably has one or more openings in a piston skirt, so that when the shut-off valve is open, the gaseous medium can flow from the interior of the hollow piston via the openings to the outside and past the open second sealing seat in the direction of the gas injector.

[0018] An elastomer sealing element is particularly preferably provided at the second sealing seat. Since the second sealing seat in a direct-injection gas injector is located somewhat away from the combustion chamber, an elastomer can be used as the sealing element, which offers significant advantages in terms of permanent tightness at the second sealing seat. The use of an elastomer sealing element preferably also enables the use of a larger sealing surface between the sealing partners, which further improves the tightness of the second sealing seat.

[0019] Further preferably, the control valve unit is configured to connect the vacuum port to a pressure range in which the pressure of the gaseous medium to be injected prevails, in order to also close the second sealing seat. Thus, it is possible for the control valve unit to be configured to both open and close the shut-off valve.

[0020] The control valve unit preferably has a first and a second control valve. The first control valve is designed to establish and interrupt a fluid connection between the vacuum connection and the vacuum source. The second control valve is designed to establish and interrupt the fluid connection between the vacuum connection and the pressure region of the gaseous medium. The control valve unit thus comprises two separate control valves, which can also be controlled separately, whereby the design of the gas injector arrangement can nevertheless be implemented particularly cost-effectively. The first control valve is arranged between the vacuum connection and the vacuum source, and the second control valve is arranged between the vacuum connection and the pressure region of the gaseous medium. As a result, a line leading from the vacuum connection forms a branch line in a Y-shape, with a control valve arranged on each branch of the Y-shape.Particularly preferably, the first and second control valves are constructed identically.

[0021] The gas injector arrangement further preferably comprises a control unit which is configured to close the first control valve at the start of injection by means of the gas injector such that the vacuum connection is connected to the vacuum source in order to open the second sealing seat of the gas injector at the shut-off valve. As soon as the second sealing seat is opened, the control unit is further configured to close the first control valve again. This makes it possible to ensure that the second sealing seat remains in the open position without a constant connection to the vacuum source. This makes it possible, in particular, to avoid losses of the gaseous medium, which can occur with a continuous connection between the vacuum connection and the vacuum source due to outflowing gaseous medium. The second control valve is closed in this case.

[0022] More preferably, the gas injector further comprises a pressure sensor arranged on a line connecting the vacuum port to the control valve unit. The control unit is configured to briefly open the first control valve when the pressure sensor detects a pressure increase in the line above a predetermined threshold during an injection operation of the gas injector. This connects the vacuum port to the vacuum source, resulting in a further reduction in pressure in the line. As soon as the pressure sensor detects that the pressure in the line is again below the predetermined threshold, the first control valve is closed again. This ensures safe operation of the gas injector.

[0023] According to an alternative preferred embodiment of the invention, the control valve unit comprises precisely one control valve, which is designed as a 2 / 2-way valve. This enables a particularly simple and cost-effective design. The 2 / 2-way valve preferably comprises a first and a second conical seat, as well as a ball-shaped actuating element that seals against the first conical seat or the second conical seat. A compression spring ensures that the 2 / 2-way valve is held in the initial position, closed to the vacuum source.

[0024] Further preferably, the gas injector arrangement comprises a line piece, in particular a connecting pipe, which establishes a connection between the gas injector and the shut-off valve. A screw connection is preferably formed between the line piece and the gas injector, as well as between the line piece and the shut-off valve.

[0025] Furthermore, the present invention relates to an internal combustion engine with a gas injector arrangement according to the invention. The internal combustion engine preferably comprises an intake manifold of the internal combustion engine as a vacuum source, which is fluidly connected to the shut-off valve via the control valve unit. An opening of a connecting line between the intake manifold and the shut-off valve is preferably located downstream of a throttle valve in the intake manifold. Further preferably, the vacuum source is a catalyst of the internal combustion engine.

[0026] Preferably, the internal combustion engine comprises a plurality of gas injectors arranged in series on the rail at respective branch bores of the rail. Thus, a cost-effectively constructed internal combustion engine for using gaseous fuels can be provided, which, using the rail, ensures a reliable supply of the respective gas injectors with the gaseous medium to be injected.

[0027] Short description of the drawings

[0028] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0029] Figure 1 is a schematic sectional view of a gas injector arrangement according to a first embodiment of the invention in the closed state of the gas injector,

[0030] Figure 2 is a schematic, enlarged view of a

[0031] Shut-off valve of the gas injector arrangement of Figure 1 in the closed state,

[0032] Figure 3 is a schematic, enlarged view of a

[0033] Shut-off valve of the gas injector arrangement of Figure 1 in the open state,

[0034] Figure 4 is a schematic side view of a rail of a

[0035] Gas injector arrangement of Figure 1,

[0036] Figure 5 is a schematic sectional view of a gas injector arrangement according to a second embodiment of the invention in the closed state, and

[0037] Figure 6 shows a schematic representation of a gas injector arrangement according to a third embodiment of the invention in the closed state. Preferred embodiments of the invention

[0038] A gas injector arrangement 111 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 to 4.

[0039] As can be seen from Figure 1, the gas injector arrangement 111 comprises a gas injector 1, a shut-off valve 300, a control valve unit 8 and a rail 400.

[0040] The gas injector 1 comprises a closing element 2 in the form of a valve needle and an actuator 5. The gas injector is configured to inject a gaseous medium, in particular hydrogen, into a combustion chamber 30. The actuator 5 is configured to actuate the closing element 2 to bring it into an open position. Figure 1 shows the closed state of the gas injector.

[0041] The actuator 5 is a magnetic actuator with an armature 50 and an inner pole 51. The actuator 5 is arranged in a closed actuator chamber 53, which is shown schematically. The actuator chamber 53 is sealed from the gaseous medium in a gas chamber 10 by means of a flexible metal membrane 52.

[0042] The closing element 2 releases a through-opening 3 at a first sealing seat 4 and closes it. When the gas injector 1 is open, the gaseous medium is injected into the combustion chamber 30. A return element 6, for example a cylinder spring, returns the closing element 2 to the closed initial position shown in Figure 1.

[0043] The gas injector 1 has a very compact and, in particular, short design in the axial direction XX. The gaseous medium to be injected is introduced into the gas injector through an inlet nozzle 11 and flows around the enclosed actuator chamber 53, with corresponding openings formed in the respective components.

[0044] As shown in Figure 1, the shut-off valve 300 is arranged on the gas injector 1 at the inlet connection 11. The shut-off valve 300 provides a second sealing seat 7 of the gas injector assembly. The shut-off valve 300 is designed as a pre-assembled module and is arranged in the gas flow direction A between the gas injector and the rail 400.

[0045] As can be seen from Figure 1, the shut-off valve 300 is arranged almost entirely in the rail 400 in order to save installation space.

[0046] The shut-off valve 300 comprises a substantially hollow-cylindrical main body 301, in which a piston 302 is arranged for axial movement. The piston 302 is preloaded in the axial direction XX by a closing spring 305. The piston 302 is designed as a hollow cylinder closed on one side and has an elastomer sealing element 306 on one end face. The elastomer sealing element 306 seals a connecting piece 304 of the shut-off valve 300, which is designed as a housing component and establishes a connection to the gas injector 1. The piston 302 has a plurality of lateral openings 303.

[0047] Figures 2 and 3 show the shut-off valve 300 in detail. Figure 2 shows the closed state, in which the elastomer sealing element 306 rests against the connecting piece 304 and closes the second sealing seat 7. The gas flow path through the open shut-off valve 300 is indicated by arrows A in Figure 3.

[0048] The shut-off valve 300 further comprises a first radial seal 311 and a second radial seal 312. The two radial seals 311, 312 are arranged on the outer circumference of the main body 301 at an axial distance from one another. The two radial seals 311 and 312 seal the shut-off valve 300 against the rail 400 in a transverse bore 402. Between the two radial seals 311, 312, a vacuum connection 80 is located on the shut-off valve 30. The vacuum connection 80 is connected to the gas-conducting region of the shut-off valve 300 via a gap 313, a control chamber 307, an axial bore 308, and a radial bore 309 (see Figure 2).

[0049] A further elastomer seal 310 is arranged on the piston 302, which, when the shut-off valve 300 is fully open, closes the axial bore 308 at a third sealing seat 330. This interrupts the connection between the gas-conducting area of ​​the shut-off valve 300 and the vacuum connection 80. Thus, the two elastomer seals 310 and 306 are not in the closed state at the same time.

[0050] The gas injector arrangement 111 further comprises a control valve unit 8, which comprises precisely one control valve 81, which is designed as a 2 / 2-way valve. The control valve 81 is configured to connect the vacuum port 80 to a vacuum source 82 and to interrupt the connection. In this exemplary embodiment, the vacuum source 82 is an intake manifold of an internal combustion engine. The intake direction is indicated in Figure 1 by arrow B in the intake manifold. An opening of a line 83 is located downstream of a throttle valve 84 in the intake direction.

[0051] The rail 400 is designed in a known manner as a distributor pipe and comprises a main bore 401 and a transverse bore 402. The shut-off valve 300 is arranged almost entirely within the transverse bore 402. The vacuum connection 80 is also positioned in the rail 400. It should be noted that, as shown in Figure 4, several transverse bores 402 branch off from the main bore 401. A shut-off valve 300 with a connected gas injector is arranged in each transverse bore 402.

[0052] As is clear from the closed state of the gas injector arrangement 111 shown in Figure 1, the gas injector arrangement 111 thus comprises two closed sealing seats 4 and 7 in the closed state. The second sealing seat 7 can be designed as an elastomer sealing seat and provides particularly good sealing performance. The second sealing seat 7 can thus provide very good sealing in the closed state, so that even if the gas injector is idle for an extended period, no gas can penetrate into the gas chamber 10 via the second sealing seat 7. Thus, in the closed state of the gas injector arrangement, a maximum gas loss of a gas volume that was present between the first and second sealing seats in the gas injector 1 results.

[0053] The function of the gas injector arrangement 111 according to the invention is as follows: When the internal combustion engine is started, a negative pressure is generated in the intake manifold, thereby providing the negative pressure source 82. When the internal combustion engine is started, the control valve 81 is simultaneously moved from the closed position shown in Figure 1 to the open position. As a result, the control chamber 307 is connected to the negative pressure source 82 via the line 83. As a result, the pressure in the control chamber 307 drops, so that the piston 302 of the shut-off valve 300 moves in the direction of arrow C, starting from the closed position shown in Figure 2. The movement of the piston 302 occurs against the force of the closing spring 305. As a result, the second sealing seat 7 is opened.

[0054] Figure 3 shows the fully open state of the shut-off valve 300, with the elastomer seal 310 closing the fluid path between the gas-conducting area of ​​the shut-off valve 300 and the control valve 81 at the third sealing seat 330. Thus, the fluid path between the gas-conducting area of ​​the shut-off valve 300 and the control valve 81 is closed.

[0055] During operation of the internal combustion engine, the control valve 81 can always remain open. The actual injection is then controlled by controlling the actuator 5 via the opening and closing closure element 2. The shut-off valve 300 thus always remains open during operation of the internal combustion engine.

[0056] Since the second sealing seat 7 is opened by means of vacuum, it is possible to select a very large seat diameter for the second sealing seat. This results in space savings, since the gaseous medium has a much larger volume than liquid fuels, so it must be injected into the combustion chamber in a short time.

[0057] When the internal combustion engine is shut down, the control valve 81 is closed again by interrupting the current supply to the control valve. Pressure builds up again in the control chamber 307 via the gap 313, which, together with the closing spring 305, resets the shut-off valve 300 to the closed state shown in Figure 2. Thus, when the internal combustion engine is shut down, the gas injector assembly 111 is closed at the first and second sealing seats.

[0058] Furthermore, a vacuum bore 403 is provided in the rail 400, which connects the vacuum connection 80 to the control valve 81. The control valve 81 is preferably arranged directly at an opening of the vacuum bore 403. This eliminates the need for long, complex pressure lines between the shut-off valve 300 and the control valve 81. In Figure 1, the connection between the control valve 81 and the vacuum bore 403 is shown only schematically. As shown in Figure 4, the control valve 81 is arranged directly on the rail 400. The vacuum bore 403 connects all vacuum connections of the shut-off valves 300 of each gas injector to one another simultaneously (see Figure 4). Thus, only one control valve is necessary.

[0059] Thus, the gas injector 111 has a very compact design that requires little installation space. Furthermore, the gas injector 1 can be designed to be very short, particularly in the axial direction XX, resulting in space savings on the internal combustion engine. The effort required for pressure lines, particularly the connection between the shut-off valves 300 and the control valve 81, can also be reduced. This enables significant cost savings. Significant advantages also arise during assembly, since both the gas injector 1 and the shut-off valve 300 and the rail 400 can be provided as preassembled assemblies.

[0060] Figure 5 shows a gas injector assembly 111 according to a second embodiment of the invention. Identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.

[0061] The second embodiment essentially corresponds to the first embodiment, except that the control valve unit 8 has a different structure. The control valve unit 8 comprises a first control valve 100 and a second control valve 200. The two control valves 100, 200 are identically constructed. The control valve unit 8 further comprises a control unit 13, which can individually control the first and second control valves 100, 200 to open or close them.

[0062] Furthermore, the control valve unit 8 comprises a pressure sensor 14. The pressure sensor 14 is also connected to the control unit 13.

[0063] The gas injector 1 and the shut-off valve 300 are constructed as in the first exemplary embodiment. As can be seen from Figure 5, the vacuum connection 80 on the shut-off valve 300 is again connected to the vacuum bore 403 in the rail 400. The vacuum bore 403 is connected to a drain line 87, which branches into a first branch line 88 and a second branch line 89.

[0064] The first control valve 100 has a first sealing seat 101 for opening and closing a passage opening. The second control valve 200 has a second sealing seat 201 for opening and closing a passage opening. The first control valve 100 further includes an inlet connection 102 and is designed as a solenoid valve. The second control valve 200 also includes an inlet connection 202 and is designed as a solenoid valve.

[0065] The first branch line 88 leads from the drain line 87 to the inlet connection 102 of the first control valve 100. The first sealing seat 101 is connected to the vacuum source 82 via a line 83. The inlet connection 202 of the second control valve 200 is connected to a supply line 120, which contains the pressurized medium to be injected. The supply line 120 leads to the rail, more precisely to the main bore 401 of the rail 400.

[0066] The control valve unit 8 is thus connected to the vacuum connection 80 of the shut-off valve 300 and is configured to connect the vacuum connection 80 to the vacuum source 82 in order to open the second sealing seat 7 in the shut-off valve 30.

[0067] The function of the gas injector arrangement 100 of the second exemplary embodiment is as follows: When the internal combustion engine is started, a vacuum is generated in the intake manifold, thereby providing the vacuum source 82. When the internal combustion engine is started, the first control valve 100 is simultaneously energized, so that it is moved from the closed position shown in Figure 5 to the open position. The second control valve 200 remains closed. Thus, the vacuum connection 80 is connected to the vacuum source 82 via the first control valve 100.

[0068] During operation of the internal combustion engine, the first control valve 100 is continuously kept open, so that the second sealing seat 7 of the shut-off valve 300 is always open for the injection of gaseous medium. When the internal combustion engine is shut off, the first control valve 100 is closed and the second control valve 200 is opened. As a result, pressurized gaseous medium flows from the supply line 120 through the open second control valve 200 and the second branch line 89 into the drain line 87 in the direction of the vacuum connection 80. This increases the pressure in the control chamber 307, so that the shut-off valve 300 is returned to the closed state with the assistance of the closing spring 305.

[0069] Thus, although the control valve unit 8 of the second embodiment has two separate control valves 100, 200, a very simple and cost-effective construction can still be realized since, on the one hand, both control valves 100, 200 are constructed identically and, on the other hand, the two control valves 100, 200 can be controlled very easily.

[0070] Figure 6 shows a gas injector arrangement 111 according to a third exemplary embodiment of the invention. Identical or functionally identical parts are again designated by the same reference numerals as in the previous exemplary embodiments. The third exemplary embodiment essentially corresponds to the first exemplary embodiment, although, in contrast to the first exemplary embodiment, in the third exemplary embodiment the gas injector 1 and the shut-off valve 30 are spatially separated. A connecting pipe 15 is provided which connects the gas injector 1 to the shut-off valve 300. This allows a spatial separation of the gas injector 1 and the shut-off valve 300 to be realized. The connecting pipe 15 can be rigid or flexible. A secure, fluid-tight connection between the connecting pipe 15 and the gas injector 1 and the shut-off valve 300 is realized by a first screw connection 16 and a second screw connection 17.Additional sealing elements can also be used to improve the tightness of the connections. Otherwise, this embodiment corresponds to the first embodiment, so reference can be made to the description given there.

Claims

Claims 1. Gas injector arrangement for injecting a gaseous medium, comprising: a gas injector (1), a shut-off valve (300), a control valve unit (8) and a rail (400), wherein the gas injector comprises: a closing element (2) which opens and closes a through-opening (3) at a first sealing seat (4), an actuator (5) for actuating the closing element (2), and a reset element (6) for resetting the closing element (2), wherein the shut-off valve (300) is arranged between the gas injector (1) and the rail (400) and comprises: a second sealing seat (7) which is arranged upstream of the gas injector (1) in the flow direction of the gaseous medium, wherein the second sealing seat (7) opens and closes a gas flow path (A) through the shut-off valve (300), and a vacuum connection (80) which is arranged upstream of the second sealing seat (7) is arranged, and wherein the control valve unit (8) has a control valve (81;100, 200) which is in fluid communication with the vacuum port (80) and is configured to connect the vacuum port (80) to a vacuum source (82) in order to open the second sealing seat (7); 2. Gas injector arrangement according to claim 1, wherein the rail (400) has a main bore (401) for supplying the gaseous medium and a vacuum bore (403), wherein the vacuum bore (403) provides a fluid connection between the vacuum connection (80) and the control valve unit (8).

3. Gas injector arrangement according to one of the preceding claims, wherein the rail (400) has a transverse bore (402), wherein the shut-off valve (300) is arranged in the transverse bore (402).

4. Gas injector arrangement according to claim 3, wherein a first radial seal (311) and a second radial seal (312) are arranged between the shut-off valve (300) and the transverse bore (402) in the rail (400), wherein the vacuum connection (80) is arranged in the axial direction between the first and second radial seals (311, 312).

5. Gas injector arrangement according to one of the preceding claims, wherein the shut-off valve (300) comprises an axially movable piston (302) which is configured to release and close the second sealing seat (7).

6. Gas injector assembly according to claim 5, wherein the shut-off valve (300) has a third sealing seat (330) on the piston (302) to open and close a fluid connection to the vacuum port (80).

7. Gas injector arrangement according to one of claims 4 to 6, wherein the piston (302) of the shut-off valve (300) is a hollow piston which seals at a piston end face on the second sealing seat (7).

8. Gas injector arrangement according to one of claims 4 to 7, further comprising a control chamber (307) which is formed on an outer circumference of the piston element (302) and lies in a connecting path between a gas-conducting inner region of the shut-off valve (300) and the control valve unit (8).

9. Gas injector arrangement according to one of the preceding claims, wherein the second sealing seat (7) comprises an elastomer seal (306).

10. Gas injector arrangement according to one of the preceding claims, wherein the control valve unit (8) comprises a first control valve (100) and a second control valve (200), wherein the first control valve (100) establishes and interrupts a fluid connection between the vacuum port (80) and the vacuum source (82), and wherein the second control valve (200) establishes and interrupts a fluid connection between the vacuum port (80) and a pressure region of the gaseous medium.

11. Gas injector arrangement according to claim 10, further comprising a control unit (13) which is configured to switch the first control valve (100) at the start of injection by means of the gas injector (1) such that the vacuum connection (80) of the shut-off valve (300) is connected to the vacuum source (82) in order to open the second sealing seat (7).

12. Gas injector arrangement according to claim 11, further comprising a pressure sensor (14) which is arranged on a line connected to the vacuum connection (80), wherein the control unit (13) is configured to briefly open the first control valve (100) when the pressure in the line exceeds a predetermined threshold value during operation of the gas injector, as detected by the pressure sensor (14), in order to achieve a pressure reduction in the line by connecting it to the vacuum source (82).

13. Gas injector arrangement according to one of claims 1 to 9, wherein the control valve unit (8) has exactly one control valve (81), which is a 2 / 2-way valve.

14. Gas injector arrangement according to one of the preceding claims, wherein a connecting pipe (15) is arranged between the gas injector (1) and the shut-off valve (300).

15. Internal combustion engine comprising a gas injector arrangement according to one of the preceding claims, wherein the vacuum source (82) is in particular an intake region of the internal combustion engine.

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